The present invention relates to trim strips or molding and, more particularly, to a trim strip or molding manufactured from an injection process or extruding with a post form process.
In commonly known injection molding operations, generally the molds or dies utilized in the operation are very heavy, sturdy and durable. This is due to the fact that the material injected into the molds or dies is at elevated temperature and pressure. Thus, the molds must be very strong and durable to endure the increased temperature and pressure which also explains their high cost.
During the manufacturing of trim strips or molding, especially trim strips for vehicles, which utilize adhesive strips to position the trim strips onto the vehicle, a primer or barrier must be positioned between the outer plastic molding and the adhesive tape. The barrier is needed to prevent eventual migration of plasticizer from the molding to the adhesive tape which would, in time, destroy the bond of the adhesive tape to the molding. Thus, a very thin film of aluminum, rigid vinyl, or the like including chemical barrier coatings have been utilized to prevent migration of plasticizer to the adhesive tape.
Thus, it is desirous to have trim strips and a method of manufacturing trim strips which overcome the above disadvantages. Accordingly, the present invention provides the art with a trim strip which overcomes the above disadvantages.
The present invention provides the art with a trim strip which is manufactured by a molding process. The molding occurs at very low pressure, if any, to enable utilization of low cost lightweight molds or dies. The trim strip or molding is formed by dispensing liquid plastic into a mold and applying heat to solidify the plastic. The trim strip is cooled and reheated to heat the exposed surface of the strip. Adhesive tape or adhesive tape applied to a hard plastic strip to form a separate laminate is bonded to the plastic surface soon after completion of the second heating cycle. Additionally, a force may be applied to the backing member to enhance the bond between the two. Another advantage of the second heating step is that the molding flash is greatly reduced or completely eliminated. Also, the portion of the molded plastic outside of the attaching tape is generally more pointed and is better suited to form an effective tape skirt. (The tape skirt is that portion of the outer molding that partially blocks out the appearance of the attaching tape after assembly to the auto body.) The hard plastic strip or aluminum effectively acts as a barrier and prevents plasticizer from migrating from the solidified plastic which in time would destroy the bond between the adhesive tape and the solidified plastic. Plastics that can be used in this invention may be liquid vinyls such as plastisols. The hard plastic strip may be vinyl made in conventional extruding or calandering methods. The present invention, which is molded at very low pressure, produces trim strips which are color nondirectional and substantially eliminate metallic flop.
Also, on account of the low pressure, trim strips with large abrupt changes in thickness may be manufactured without "sinks" on the finished surface. This characteristic is becoming more important due to the trend of new designs requiring high gloss smooth surfaces on new automotive applications where sinks are more noticeable. It is also important for the new designs to incorporate weight saving features which can be achieved by hollowing out bottom portions of the trim strip.
This molding process also exhibits advantageous surface adherence capability when the molding is finally attached to a surface. A suitable tension force may be applied to the adhesive tape when the laminate is manufactured so that the completed molding is either straight or lengthwise curved so that the taped surface is lengthwise concaved.
From the subsequent detailed description taken in conjunction with the accompanying claims and subjoined drawings, other objects and advantages of the present invention will become apparent to those skilled in the art.